The use of power hand tools, such as an electric power drill, have become commonplace in various household applications. Electric power drills are employed for such tooling operations as drilling holes and driving fasteners. Many of these, and other, applications of power tools dictate that the tool operation be performed in a physically-constrained region, such as an acutely-angled corner or a narrow recess. Consequently, the use of a power tool becomes limited if any external dimension thereof prohibits the tool to be properly positioned in the physically constrained region.
Many electric power drills comprise a housing which encloses a drill motor and a nose cone which contains a gear case for transferring rotational power from a shaft of the motor to a bit mounted in the drill. The assembling of the power drill includes a step of fastening the nose cone to the housing. Various assemblies having been proposed for fastening the nose cone to the housing. In early electric drill designs, the nose cone was threadably fastened to the housing. These designs resulted in either a weakly-fastened nose cone or an expensively-manufactured drill.
U.S. Pat. No. 3,908,139 to Duncan, Jr. discloses a portable power tool having a nose cone joined to first and second clam shell housing segments by an annular fastener receiving member seated in a groove in the housing. The nose cone is joined to the housing by fasteners which pass axially through the nose cone for reception by the fastener receiving member. U.S. Pat. No. 4,730,134 to Sistare discloses a portable power tool having a nose cone joined to first and second clam shell housing segments by a bearing plate fastened to walls of the housing. The nose cone is then clamped to the housing segments by screws which pass axially through the nose cone for reception by the bearing plate.
Since the size of the housing and the nose cone contributes to the external dimensions of the tool, the scope of application of the tool must be regarded when designing an assembly for fastening the nose cone to the housing. In both of the above-mentioned arrangements, at least one transverse dimension of the nose cone extends to sufficiently accommodate the head of each of the fastening screws. Such arrangements are disadvantageous in applications where a tool operation must be performed in regions having limited space available for transverse dimensions of the nose cone.